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Lecture-7 Lists in Python

Lists

Lists are used to store multiple items in a single variable.

Example :

Students=['Yash','Vidya','Gauri']
print(Students)
Students=['Yash','Vidya','Gauri','Prachi']
print(Students[1])
Students=['Yash','Vidya','Gauri','Prachi']
print(Students[0:3])
Students=['Yash','Vidya','Gauri','Prachi']
print(Students[-1])

Properties Of List

  1. Ordered

Lists are ordered, it means that the items have a defined order, and that order will not change.

  1. Allow Duplicates

Lists can have items with the same value

Fruits = ["apple", "banana", "cherry", "apple", "cherry"]
print(Fruits)
  1. List can contain Different Data Type

A list can contain different data types

RandomData = ["abc", 34, True, 40, "Hi"]
print(RandomData)
  1. Changeable

The list is changeable, that we can change, add, and remove items in a list after it has been created.

  • Update =
Courses=['c','c++','Python','Java']
print("Before Changes",Courses)
Courses[1]="C++ Programming"
print("After Changes",Courses)
  • Insert =
Courses=['c','c++','Python','Java']
print("Before Changes:",Courses)
Courses.insert(1,'Android Development')
print("After Changes:",Courses)
  • Append =

The append() method appends an element to the end of the list.

Courses=['c','c++','Python','Java']
print("Before Changes:",Courses)
Courses.append('Android Development')
print("After Changes:",Courses)
  • Remove =

The remove() method removes the specified item.

Fruits = ["apple","banana","orange","grepes"]
Fruits.remove("banana")
print(Fruits)
  • Pop =

The pop() method takes a single argument (index).

Fruits = ["apple","banana","orange","grepes"]
Fruits.pop(2)
print(Fruits)
  • Delete =
Fruits = ["apple","banana","orange","grepes"]
del Fruits[1]
print(Fruits)
  • Clear =

The clear() method removes all the elements from a list.

Fruits = ["apple","banana","orange","grepes"]
Fruits.clear()
print(Fruits)
  • Sort =

List objects have a sort() method that will sort the list alphanumerically, ascending,descending.

Ascending Order=

alphabets=['A','R','V','S','P']
alphabets.sort()
print(alphabets)

Descending Order=

alphabets=['A','R','V','S','P']
alphabets.sort(reverse=True)
print(alphabets)

🏠 HomeWork

1️⃣Write a program to implement deletion of items from list using four different methods.

👁 Show Answer 

colour=["Red","Pink","Orange","Yellow","Green"]
colour.remove("Pink")
print(colour)       #Remove Method

colour=["Red","Pink","Orange","Yellow","Green"]
colour.pop(3)
print(colour)       #Pop Method

colour=["Red","Pink","Orange","Yellow","Green"]
del colour[1]
print(colour)       #Delete Method

colour=["Red","Pink","Orange","Yellow","Green"]
colour.clear()
print(colour)       #Clear Method

2️⃣ Write a program to implement sort the given list in ascending and descending order.

👁 Show Answer 

colour=["Red","Pink","Orange","Yellow","Green"]
colour.sort()
print(colour)       #Ascending order

colour=["Red","Pink","Orange","Yellow","Green"]
colour.sort(reverse=True)
print(colour)       #descending order

🔗 Some Useful Links

📖 References